The purpose of this project is to develop methods for gene transfer to mammalian cells and to use these techniques for gene mapping, analysis of gene expression, and cloning eukaryotic genes. A large number of independent somatic cell hybrid lines segregating human chromosomes have been isolated and the human chromosome content of each line determined. Analysis of these lines with isotopically labeled cloned DNA probes has allowed assignment to specific human chromosomes of the human cellular analogues of four viral onc genes as well as kappa, lambda and heavy chain immunoglobulin (Ig) genes and four Ig pseudogenes. Heavy chain V, D, J and C genes have all been regionally localized to a single chromosomal band (14q32) and one onc gene has been regionally assigned on chromosome 6. Chromosomal assignment of these genes now permits a rational assessment of the possible role of onc genes in human cancer. DNA-mediated gene transfer is being used in combination with recombinant DNA techniques to isolate and analyze the human tk gene. Transformants resulting from chromosome-mediated gene transfer have been characterized and used to map repetitive DNA sequences on the human X chromosome.